as in treacherous
formal
causing harm in a way that is gradual or not easily noticed
Most people with this insidious disease have no idea that they are infected. an insidious enemy
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Example Sentences
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Recent Examples of insidious
The work of documentaries must be rigorous, contextualized, and unflinching enough to help stop the progression of an insidious message and movement.
—
Alison Foreman, IndieWire, 19 Mar. 2026
The show, which runs through March 28, has a blistering message to impart about the insidious nature of authoritarian political movements and the dangers of being oblivious or indifferent.
—Christopher Arnott, Hartford Courant, 18 Mar. 2026
But the kind of harassment that may not rise to the level of a crime in most countries – more pervasive and more subtle, but nonetheless insidious – has largely remained unacknowledged in Brazilian jiu-jitsu.
—Ina Seethaler, The Conversation, 4 Mar. 2026
Moderate beauty, yet insidious.
—Literary Hub, 2 Mar. 2026
See All Example Sentences for insidious
Alison Foreman, IndieWire, 19 Mar. 2026
The show, which runs through March 28, has a blistering message to impart about the insidious nature of authoritarian political movements and the dangers of being oblivious or indifferent.
—Christopher Arnott, Hartford Courant, 18 Mar. 2026
But the kind of harassment that may not rise to the level of a crime in most countries – more pervasive and more subtle, but nonetheless insidious – has largely remained unacknowledged in Brazilian jiu-jitsu.
—Ina Seethaler, The Conversation, 4 Mar. 2026
Moderate beauty, yet insidious.
—Literary Hub, 2 Mar. 2026
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
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In the film, Tshiring Lhamu Lama and Tenzin Bhuti Gurung journey through the treacherous and breathtaking Himalayas in search of endangered snow leopards.—
Stewart Clarke,
Deadline,
9 Apr. 2026
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Oatman was a destination along one of the original alignments of Route 66 via a treacherous path through the Black Mountains, but it was later bypassed as part of improvements made in the 1950s.—
Susan Montoya Bryan,
Los Angeles Times,
8 Apr. 2026
Adjective
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One search can yield a long list of options, each with its own rules, conditions, and subtle differences that are easy to miss at first glance.—
Matthew Kayser,
Miami Herald,
8 Apr. 2026
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However, a slight blurring of stars at the edge of the frame seems to betray the subtle motion of the spacecraft — or camera — over the course of the 10-second exposure.—
Anthony Wood,
Space.com,
8 Apr. 2026
Adjective
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Naturally, Yuga Labs sued Ripps, and his partner Cahen, alleging false advertising, trademark infringement, and cybersquatting.—
Harrison Jacobs,
ARTnews.com,
10 Apr. 2026
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Because of this, Becerra is also facing a misdemeanor count of attempting to induce false testimony.—
Nicole Macias Garibay,
Los Angeles Times,
10 Apr. 2026
Adjective
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In the class action suit, Rodriguez requested a jury trial, damages, restitution and injunctive relief to prevent Hollister from continuing to use its alleged deceptive pricing practices.—
Jennifer Bringle,
Footwear News,
6 Apr. 2026
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Samuel Nana Opoku, a resident of Fairfax County, Virginia, is facing charges of money laundering, felony theft by taking, five counts of identity fraud, and initiation of deceptive commercial email.—
Dan Raby,
CBS News,
2 Apr. 2026
Adjective
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The government took a genuine invitation to collaborate as a perfidious power grab.—
Gideon Lewis-Kraus,
New Yorker,
14 Mar. 2026
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For those trying to read Iran’s future, the lesson of 1953 is not just that foreign powers can be perfidious.—
Bobby Ghosh,
Time,
5 Mar. 2026
Adjective
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Google disputes the results and notes that Oumi used the SimpleQA benchmark, an AI test developed by OpenAI that contains incorrect information in its own right.—
Jon Martindale,
PC Magazine,
8 Apr. 2026
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Google spokesperson Ned Adriance tells the Times that Google believes SimpleQA contains incorrect information.—
ArsTechnica,
ArsTechnica,
7 Apr. 2026
Adjective
-
Sometimes that’s totally wrong, because people are overestimating their kids or underestimating Joan Mitchell or whomever.—
Andrew Marantz,
New Yorker,
5 Apr. 2026
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Or show off the Sombor Shuffle with an 11-footer off the wrong foot.—
Troy Renck,
Denver Post,
5 Apr. 2026
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 11 Apr. 2026.
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